proc: switch /proc/meminfo to seq_file

and move it to fs/proc/meminfo.c while I'm at it.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 27efa14..70607a0 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -10,6 +10,7 @@
 proc-y       += inode.o root.o base.o generic.o array.o \
 		proc_tty.o proc_misc.o
 proc-y	+= loadavg.o
+proc-y	+= meminfo.o
 proc-y	+= uptime.o
 proc-$(CONFIG_PROC_SYSCTL)	+= proc_sysctl.o
 proc-$(CONFIG_NET)		+= proc_net.o